#include <cstdio>
#include <cstring>

int graph[21][21];

int main(int argc, char const* argv[])
{
    int n;
    scanf("%d", &n);
    char str[201];
    scanf("%s", str);
    int row = strlen(str) / n;
    int index = 0;
    for (int i = 0; i < row; i++) {
        if ((i + 1) % 2 != 0) {
            for (int j = 0; j < n; j++)
                graph[i][j] = str[index++];
        } else {
            for (int j = n - 1; j >= 0; j--)
                graph[i][j] = str[index++];
        }
    }
    for (int j = 0; j < n; j++) {
        for (int i = 0; i < row; i++) {
            printf("%c", graph[i][j]);
        }
    }
    return 0;
}